netdev - [PATCH net-next v2 06/15] net: sched: act_pedit: remove dependency on rtnl lock

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Date:   Fri, 10 Aug 2018 20:51:46 +0300
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, pablo@...filter.org, kadlec@...ckhole.kfki.hu,
        fw@...len.de, ast@...nel.org, daniel@...earbox.net,
        edumazet@...gle.com, keescook@...omium.org,
        marcelo.leitner@...il.com, Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next v2 06/15] net: sched: act_pedit: remove dependency on rtnl lock

Rearrange pedit init code to only access pedit action data while holding
tcf spinlock. Change keys allocation type to atomic to allow it to execute
while holding tcf spinlock. Take tcf spinlock in dump function when
accessing pedit action data.

Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
---
 net/sched/act_pedit.c | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index 43ba999b2d23..3f62da72ab6a 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -187,44 +187,38 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla,
 			tcf_idr_cleanup(tn, parm->index);
 			goto out_free;
 		}
-		p = to_pedit(*a);
-		keys = kmalloc(ksize, GFP_KERNEL);
-		if (!keys) {
-			tcf_idr_release(*a, bind);
-			ret = -ENOMEM;
-			goto out_free;
-		}
 		ret = ACT_P_CREATED;
 	} else if (err > 0) {
 		if (bind)
 			goto out_free;
 		if (!ovr) {
-			tcf_idr_release(*a, bind);
 			ret = -EEXIST;
-			goto out_free;
-		}
-		p = to_pedit(*a);
-		if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {
-			keys = kmalloc(ksize, GFP_KERNEL);
-			if (!keys) {
-				ret = -ENOMEM;
-				goto out_free;
-			}
+			goto out_release;
 		}
 	} else {
 		return err;
 	}
 
+	p = to_pedit(*a);
 	spin_lock_bh(&p->tcf_lock);
-	p->tcfp_flags = parm->flags;
-	p->tcf_action = parm->action;
-	if (keys) {
+
+	if (ret == ACT_P_CREATED ||
+	    (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys)) {
+		keys = kmalloc(ksize, GFP_ATOMIC);
+		if (!keys) {
+			spin_unlock_bh(&p->tcf_lock);
+			ret = -ENOMEM;
+			goto out_release;
+		}
 		kfree(p->tcfp_keys);
 		p->tcfp_keys = keys;
 		p->tcfp_nkeys = parm->nkeys;
 	}
 	memcpy(p->tcfp_keys, parm->keys, ksize);
 
+	p->tcfp_flags = parm->flags;
+	p->tcf_action = parm->action;
+
 	kfree(p->tcfp_keys_ex);
 	p->tcfp_keys_ex = keys_ex;
 
@@ -232,6 +226,9 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla,
 	if (ret == ACT_P_CREATED)
 		tcf_idr_insert(tn, *a);
 	return ret;
+
+out_release:
+	tcf_idr_release(*a, bind);
 out_free:
 	kfree(keys_ex);
 	return ret;
@@ -410,6 +407,7 @@ static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 	if (unlikely(!opt))
 		return -ENOBUFS;
 
+	spin_lock_bh(&p->tcf_lock);
 	memcpy(opt->keys, p->tcfp_keys,
 	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 	opt->index = p->tcf_index;
@@ -432,11 +430,13 @@ static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 	tcf_tm_dump(&t, &p->tcf_tm);
 	if (nla_put_64bit(skb, TCA_PEDIT_TM, sizeof(t), &t, TCA_PEDIT_PAD))
 		goto nla_put_failure;
+	spin_unlock_bh(&p->tcf_lock);
 
 	kfree(opt);
 	return skb->len;
 
 nla_put_failure:
+	spin_unlock_bh(&p->tcf_lock);
 	nlmsg_trim(skb, b);
 	kfree(opt);
 	return -1;
-- 
2.7.5